Artifacts resembling VT and VF

Artifacts resembling ventricular tachycardia and fibrillationArtifacts resembling ventricular tachycardia

Artifacts in an ECG can mimic various pathological conditions. In V1, multiple small artefacts almost totally obscure the small QRS complexes so that at one look it mimics ventricular fibrillation. Close scrutiny with comparison with other leads enables recognition of QRS complexes within the artifacts by their timing with other QRS complexes simultaneously recorded in other leads like V3, where the amplitude of the artifacts are much lower than that of the QRS complexes.

In V2, certain artifacts resemble a wide QRS tachycardia. The fact that it has not affected the regular QRS rhythm in other simultaneously recorded leads indicate that these are artifacts and not a run of polymorphic ventricular tachycardia. This also illustrates the advantage of monitoring multiple leads simultaneously while observing for arrhythmias. In this case a single lead V1 monitoring could lead to initiation of cardiopulmonary resuscitation if one is not vigilant enough to follow the regular pre-CPR sequence for identification of cardiac arrest before initiating chest compressions. Pre-CPR sequence will reveal a fully conscious and oriented person if there is no other reason to have altered sensorium, with a good hemodynamic status as well.

Similarly monitoring of V2 could lead to an ‘inappropriate shock’ external direct current shock being delivered. Here again, clinical assessment will avert an unnecessary DC shock which can cause much pain and distress to the person.

On the contrary, if there is simultaneous arterial pressure monitoring going on in an intensive care unit, a glance at the pressure tracing will show normal pattern in this case and asystole in polymorphic ventricular tachycardia, as reported by Long D et al [1]. In their case it was true polymorphic ventricular tachycardia! Erring on either side can be risky.

Reference

  1. Longo D, López C, García-Niebla J. Ventricular tachycardia or artifact? J Thorac Dis. 2018 Mar;10(3):2046-2047.